Alice, the sort of information which will help others is the EXIF file.  The official name of this is 
Exchangeable image file format but I think of it as "exposure information".

Yoiu might know all of this already..but I will post for anyone who does not.  You get this info from the camera display if the menu is set to allow showing exposure info.  In PSP(at least in version 8) go to Image>Image Info. In the box click the EXIF tab.

In Photoshop, right click the title bar at the top of the image window and then "camerea data" from the box that opens.

The Exif will show exposure info such as shutter speed, aperture, flash or no flash, mm of lens when shot was taken, etc.   You might also to include how far you were from the subject when the shutter was pushed.

You may need to open the original image file to get the info. Some saved files will loose the data.  Of course, we work a duiplicate or copy and not the original in editing but the original will surely have the Exif intact.

Again, best wishes.     TomDArt.